Davidian Martian Calendar
The Davidian Martian Calendar is a proposed system of time-keeping designed to serve the needs of future human settlers on the planet Mars. It was established by David Powell in Gregorian Year 1988. In 1996, a system of converting dates between Gregorian and Davidian calendars was created. Calendar Terms The Davidian calendar uses the same terminology as that used by the Gregorian calendar: Minute: Period of 60 Martian seconds (61.62s on Earth). Hour: Period of 60 Martian minutes (61m 38.968s on Earth). Day: Period of 24 Martian hours (24h 39m 35.244s on Earth). Week: A period of 7 days, same as on Earth. Month: A unit of time that on Mars simply means 1/12 of a year. Year length and intercalation The Martian year is 669.5907 Martian days long. Therefore, with very rare exceptions, every century must have 59 leap years. That means that unlike on Earth, leap years are actually more common than "common" years. Leap years are as follows: * Every even numbered year except for those that end in "00" * Every odd-numbered year that is evenly divisible by 5. Additionally, years that end in 0000, 2000, 4000, 5000, 6000, 8000, and 9000 begin with a January 0 or "Millennium Day" that does not belong to any day of the week. Calendar Layout The year is divided into 12 months. All months except for June and October have 56 days. February has 55 days during common years and 56 days during leap years. June and October have 55 days. The days of the week are the same as the Gregorian calendar, with the exception of Tuesday, which has been replaced with Gaiaday. This is because Tuesday is named after Mars and it would be more appropriate to replace it on the Martian calendar with a day that is named after Earth. *February 56th is an intercalary day that only occurs during leap years. Epoch To simplify the equation necessary to convert Gregorian dates to Martian dates, a common epoch is needed. Originally, the Gregorian epoch (January 1, 0001 CE) was used. However, it was later decided that the Davidian calendar would follow the same epoch as the Holocene calendar. This means that January 1, 0000 on the Davidian calendar is equivalent to January 1, 10001 BCE of the Gregorian calendar. This means that every date in recorded history is expressed in positive-numbered years. Calendar dates use the suffix DM, to distinguish them from BCE/BC and CE/AD (Gregorian) and HE (Holocene). For dates that occurred before the epoch, negative numbers are used. For example, 20000 years before Year 0 would be expressed as -20000 DM. Start of the year and Seasons Because the Davidian epoch is based on a common January 1st between the Davidian and Holocene calendars, the beginning of the year is completely unrelated to seasons. In fact, Martian seasons begin in months that would be strange on Earth: Rationale While other Martian calendars (notably the Darian calendar) incorporate very creative things like new names for months, days of the week, etc, the Davidian Calendar builds from what is already familiar to future settlers. Conversion The Davidian Calendar is unique among proposed Martian calendars in that it is designed to be converted back and forth between Davidian and Gregorian dates. Gregorian to Davidian The formula for converting Gregorian (Earth) dates to Davidian (Martian) dates: ( (ED + 10000) * 365.26) / 686.98 *Where "ED" = Earth Date For example: July 20, 1969 (1969.5479) is equivalent to January 55, 6364 (6364.0820). ( (1969.5479 + 10000) X 365.26) / 686.98 = 6364.0820 Davidian to Gregorian The formula for converting Davidian (Martian) dates to Gregorian (Earth) dates: ( (MD X 686.98) / 365.26) - 10000 *Where "MD" = Martian Date For example: December 2, 6365 (6365.9178) is equivalent to January 1, 1973 (1973.0006) ( (6365.9178 X 686.98) / 365.26) - 10000 = 1973.0006 Historical Events Major world historical events, shown in Davidian, Gregorian, and Holocene dates. Note: approximate "circa" dates are rounded and do not calculate directly. Holidays Holidays present a dilemma in a multi-planetary civilization. Holidays that celebrate significant historical events will probably be celebrated once per Martian year on the same date each year. Holidays of religious significance, such as Christmas, Easter, Passover, and Ramadan will probably be celebrated when they occur on Earth, regardless of what the date happens to be on Mars. This means they will occur twice annually in varying months and seasons. *Easter on Mars presumably occurs on the Martian Sunday closest to the Earth Sunday it is observed on Earth, rather than on the actual calendar date. External Links *http://akdave.wikia.com/wiki/Davidian_Martian_Calendar The Davidian Martian Calendar at the AKDave Wiki Category:Calendars intended for other places than Earth